1. Field of the Invention
This invention relates generally to a method and apparatus for the catheterization of a body cavity, and more particularly to a method and apparatus for the catheterization of a cavity between the lung and inner chest wall of a patient so that fluid may be drained therefrom.
2. Prior Art
When a patient suffers from tumors or infection involving the lungs, it is possible for fluid to collect in the chest cavity between the patient's lung and inner chest wall. Such a situation may lead to breathing difficulties, potentially endangering the patient's life. It is, therefore, common procedure to remove any such accumulated fluid, thereby improving the patient's ability to breath, and, upon analysis of the removed fluid, aiding in diagnosis of the patient's problem.
Removal of such fluid is generally accomplished using a catheter which is inserted through the patient's skin and flesh and into communication with the chest cavity. The fluid is then drained through the catheter. This procedure is known in the art as thoracentesis. Because it is a simple procedure, thoracentesis is often performed in a doctor's office, substantially decreasing the cost to the patient.
Insertion of the catheter, known in the art as catheterization, is commonly accomplished using an apparatus having a needle surrounded by a closely-fitting sheath. In previously known catheterization apparatus, it is necessary to insert both the needle and the sheath through, the flesh and into communication with the patient's chest cavity. The needle acts as a relatively aggressive penetrator, carrying the sheath with it. After penetrating the chest cavity, the needle is removed, leaving only the sheath. The sheath thereafter provides a path allowing for fluid to be drained.
If the needle is inserted too far, however, a lung may be punctured, collapsing the lung and endangering the life of the patient. Such a situation may require insertion of a chest tube to evacuate air until the lung is sealed, and usually requires emergency medical care. Additionally, time in the hospital might be involved, substantially increasing the cost of treatment.
Accordingly, it is an object of the present invention to provide a safe method and apparatus for insertion of a catheter into a body cavity. More specifically, it is an object of this invention to provide a method and apparatus wherein the extent of penetration of the chest cavity can be safely determined.